Many types of cryogenic storage units exist for various scientific or industrial purposes. These units rely on methods of refrigeration that allow items to be cooled often below −100° C. For some of coldest storage applications, liquid cryogen, such as nitrogen, is contained within a tank and the items to be stored or otherwise treated are simply immersed in this bath of liquid cryogen.
There are many previously known cryogenic storage tanks which are generally cylindrical in shape and have a closed bottom and open top thus defining a cryogenic freezing chamber. Normally, the open top has a dimension of 3 to 5¾ inches. A source of liquefied gaseous material, typically liquid nitrogen, is fluidly connected to the interior of the chamber through a valve system so that the liquid level within the cryogenic chamber is maintained within predetermined limits. A lid is also conventionally disposed across the open top of the cryogenic tank.
In use, frozen biological specimens contained in tubes or boxes, such as blood, semen or other types of biological specimens including bacteria, virus, yeast, parasite, and mammalian cells, are simply immersed in the liquid contained within the cryogenic chamber thus storing the biological materials in the desired fashion. Since the temperature of the liquefied gaseous material is extremely low, e.g. below −191° C., the viability of the biological specimens can be maintained for long periods of time.
However, it is normally not easy to move or handle these specimens-containing boxes in a removable rack out of the liquid nitrogen tanks. Necessarily, it needs at least two people or lab technicians to hold the stick of racks which containing such boxes (one operator) and look for samples within different boxes at the same time (another operator). It is not unusual to see samples and/or liquid nitrogen falling on the ground or samples falling into the liquid nitrogen tank if there is only one person handling the situation. On the other hand, if there is only one person, that person will take out the rack, put it on the ground, then take out the boxes from the rack and look for their wanted samples in the boxes. This will leave the frozen biological specimens outside the liquid nitrogen tank and at the room temperature for a while, frequently decreases the viability of the refrozen biological specimens. If the samples fall into the liquid nitrogen from the rack as mentioned above, cross contamination between the biological specimens is possible and any impurities, diseases, viruses or the like contained within that biological specimen may be transmitted to a different biological specimen also contained within the same cryogenic freezing tank.
The present invention is to provide a portable device, designed as a liquid nitrogen accessory, applicable to majority of conventional liquid nitrogen tanks. This invention provides a unique device which overcomes all of the above mentioned disadvantages in handling samples from liquid nitrogen tanks. Currently, there is neither any similar device/apparatus in the market nor any prior art found for the same purpose after comprehensive search.